In order to lower a cost at the network side and avoid congestion at the network side, in a simplified implementation at the network side, a base station directly accesses an IP network locally or through an Internet Protocol (IP) gateway without any complicated architecture and entities of a core network defined by the 3rd Generation Partnership Project (3GPP). FIG. 1 illustrates an example of a simplified architecture for an access of the base station to the network through an IP interface. The base station is also referred to as an Access Point (AP).
Particularly an IP data packet is transferred to the base station, and from the perspective of the IP network, the base station which is an IP router transfers an IP data packet, to be transmitted to a User Equipment (UE), finally to a destination. Unlike a conventional IP network, transmission from the base station to the user equipment is performed via an air interface, and the base station needs to transmit the IP data packet to the destination user equipment in an air interface addressing procedure.
There is a demand for broadcast and group-call/group-cast in cluster and industry private network applications.
Broadcast refers to transmission of information in a network segment by an information source to all of user equipments in the network segment regardless of whether this information is required. Broadcast is typically triggered by a server or a specific user equipment.
Group-call/group-cast refers to concurrent transmission of the same voice, data or video to a group of user equipments, where there is only one calling user equipment and called user equipments are all of user equipments in a group. The contents of data transmitted to the called user equipments are totally duplicated, and the use of a point-to-point transmission scheme requires multiple sets of resources and apparently will result in a waste of resources, so the use of point-to-multipoint transmission is a reasonable scheme to perform group-call and group-cast.
In the IP network, a destination address of IP broadcast is a broadcast address representing hosts throughout the network, and broadcast data is transmitted to user equipments throughout the network.
The IP multicast technology is a TCP/IP network technology to allow one or more hosts (multicast sources) to transmit a single data packet to multiple hosts (at a time and concurrently). Multicast as point-to-multipoint communication is one of effective schemes to save a network bandwidth.
With IP multicast communication dependent an IP multicast destination address, all of hosts receiving a multicast data packet using the same IP multicast destination address constitute a group of hosts, also referred to as a multicast group. A member in a multicast group may be altered at any time, and a host may belong to several multicast group.
To perform group-call/group-cast transmission in the private network, in addition to operations at the IP layer, IP-based cluster and industry private network applications require a group planed by a higher layer (e.g., the application layer), and joining or quitting of a group member is decided by an application server, and only user equipments in a group can send multicast transmission in the group.
Via an air interface, transmission between a base station and a user equipment is addressed and identified by a user equipment specific identity, i.e., a Cell Radio Network Temporary Identity (C-RNTI). The base station scrambles a scheduling command and downlink transmission data by the C-RNTI, and the user equipment receives downlink transmission and descrambles the scheduling command and the downlink transmission data by its own C-RNTI to receive scheduling and the downlink transmission, and the other user equipments can not receive the downlink scheduling and transmission of the user equipment due to their different C-RNTIs; and in the uplink direction, the user equipment scrambles uplink data by the C-RNTI so that the base station can better distinguish the user equipment from the others in reception of the uplink data.
However there has been absent so far a technology to perform IP broadcast and IP multicast transmission via an air interface, that is, a mechanism to perform IP broadcast and IP multicast transmission via an air interface in a wireless communication system where a base station accesses a network via an IP interface.